the first lesson, the teacher put an egg on the table and asked him to draw it.
A:At
B:In
C:On
下列有关我国南北方地区差异的描述不符合情况的是( )
患糖尿病的原因可能是缺乏( )
正方体ABCD﹣A1B1C1D1的棱长为l,点F、H分别为A1D、A1C的中点.
(Ⅰ)证明:A1B∥平面AFC;
(Ⅱ)证明:B1H⊥平面AFC.